Either Apple and AT&T have different policies in different stores, or your story is filled with holes.
First of all, AT&T does NOT service iphones. They send you to the Apple store if there is one local, or they send you to Apple tech support who will arrange a shipment of a new iPhone to you. AT&T does not have any new or refurb phones to give the customer, flat out they told me this. So, if you're getting DF, it's from Apple, NOT from AT&T.
Secondly, I don't know where you guys are getting this "white box" thing from, my replacement iPhone came, direct from Apple, in a plain brown box with foam padding, and inside there was a small black box that said Iphone on it (that was not sealed), but the phone was obviously brand new.